1. Field of the Invention
This invention relates to a catalyst for producing an unsaturated carboxylic acid from an alkane, a method of making said catalyst and a method of using said catalyst. In particular, this invention relates to a catalyst for producing acrylic acid from propane by a single step vapor phase oxidation reaction.
2. Description of the Prior Art
The production of an unsaturated carboxylic acid, such as acrylic acid or methacrylic acid, is conventionally done by catalytically reacting an olefin, such as propylene or isobutylene, with oxygen to form an alkenylaldehyde, such as acrolein or methacrolein, which is subsequently catalytically reacted with oxygen. Alkanes, such as propane, have advantages of cost and of availability over olefins. Furthermore, a one step process would have advantages over the present commercial process.
There are instances of producing acrylic acid and other unsaturated carboxylic acids from propane and other alkanes in a one step vapor phase catalytic oxidation reaction. U.S. Pat. No. 5,380,933 discloses a catalyst of oxides of molybdenum, vanadium, tellurium, and elements selected from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, antimony, bismuth, boron, indium or cerium. Japanese published patent application H10-57813 discloses a metal oxide catalyst of molybdenum, vanadium, tellurium and/or antimony and an element selected from niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhodium, nickel, palladium, platinum, bismuth, boron, indium, phosphorus, rare earth elements, alkali metals, alkali-earth metals. Japanese published patent application H10-45664 discloses a catalyst of oxides of molybdenum, vanadium, antimony and an element selected from niobium, tantalum, tungsten, titanium, zirconium, chromium, iron, manganese, ruthenium, cobalt, rhodium, nickel, palladium, platinum, boron, indium, alkali metals, alkali-earth metals, and rare earth elements. European published patent application 0 962 253 discloses a catalyst having oxides of molybdenum, tungsten, iron, niobium, tantalum, zirconium, ruthenium and mixtures thereof; vanadium, cerium, chromium and mixtures, thereof; tellurium, bismuth, antimony, selenium, and mixtures thereof; and niobium, tantalum, tungsten, titanium, aluminum, zirconium, chromium, manganese, iron, ruthenium, cobalt, rhenium, nickel, palladium, platinum, antimony, bismuth, boron, indium, cerium and mixtures thereof. Japanese issued patent no. 96-120,617 discloses a supported catalyst having oxides of molybdenum, vanadium, antimony, one of niobium, tantalum, tin, tungsten, titanium, nickel, iron, chromium or cobalt, and at least one of sodium, potassium, rubidium, cesium, phosphorus and arsenic. Japanese patent no. 00-246,108 discloses a catalyst having oxides of molybdenum, vanadium, antimony, at least one of niobium and tantalum and at least one of silver, zinc, tin, lead, arsenic, copper, thallium and selenium. Japanese published patent application H6-128286 disclosed a heteropolyacid catalyst having oxides of phosphorus, molybdenum, vanadium, at least one of arsenic and antimony, and at least one of tin, lead, cerium, cobalt, iron, zirconium, thorium, tungsten, germanium, nickel, rhenium, bismuth, chromium, boron, magnesium, calcium, barium, strontium, selenium, tellurium, silver, aluminum, zinc, copper, titanium, potassium, rubidium, cesium and thallium. U.S. Pat. Nos. 6,160,162 and 6,114,278 disclose a calcined catalyst having molybdenum, vanadium, gallium, palladium, niobium and at least one of lanthanum, tellurium, germanium, zinc, silicon, indium and tungsten. U.S. Pat. No. 5,994,580 discloses oxides of molybdenum, vanadium, antimony and at least one of niobium, tantalum, tin, tungsten, titanium, nickel, iron, chromium and cobalt. Japanese patent no. 11114418 discloses a catalyst having oxides of niobium, molybdenum, antimony, at least one of phosphorus, arsenic, boron, silicon and germanium and at least one of potassium, cesium, rubidium, calcium, magnesium, tellurium, chromium, manganese, iron, cobalt, nickel, cooper silver, lead, bismuth, aluminum, gallium, indium, tin, zinc, lanthanum, cerium, yttrium, tungsten, tantalum, ruthenium, rhodium, palladium, platinum, iridium, osmium, rhenium and hafnium. Chinese patent application 1,159,960 discloses bismuth based catalysts with vanadium, niobium, or tantalum and chromium, molybdenum or tungsten, optionally with lithium, sodium, potassium, copper, silver or gold. U.S. Pat. No. 4,339,355 discloses a catalyst having molybdenum, vanadium and niobium with chromium, cooper, manganese or yttrium. German patent application no. 19622331 discloses a catalyst having molybdenum, bismuth and phosphorus with vanadium, niobium, tantalum, chromium, tungsten, gallium, cerium or lanthanum; lithium, sodium, potassium, rubidium, cesium, copper, silver, gold, palladium or platinum; tin lead, antimony, bismuth, tellurium, iron, cobalt or nickel; and silicon, aluminum, titanium or zirconium. U.S. Pat. No. 5,807,531 discloses a catalyst having molybdenum and vanadium with tungsten, niobium, titanium, zirconium, hafnium, tantalum, chromium, silicon or germanium. Japanese patent application no. 246,108 (2000) discloses a catalyst having molybdenum, vanadium and antimony with niobium or tantalum and silver, zinc, tin, lead, arsenic, copper, thallium or selenium. Catalyst with similar compositions have been used for processes other than those for producing acrylic acid and other unsaturated carboxylic acids from propane and other alkanes in a one step vapor phase catalytic oxidation reaction. U.S. Pat. No. 4,250,346 discloses a catalyst for catalytically oxydehydrogenating ethane to ethylene, said catalyst having molybdenum with chromium, manganese, niobium, tantalum, titanium, vanadium or tungsten or bismuth, cerium, cobalt, copper, iron, potassium, magnesium, nickel, phosphorus, lead, antimony, silicon, tin, thallium or uranium. Japanese patent application no. 98 310,539 discloses a catalyst to form propylene from propane, said catalyst having molybdenum, vanadium and niobium.
While silver has been disclosed as a component in some of the catalysts discussed above, it is not a required component for any of these catalysts and the advantages and benefits of a catalyst composition in a one step process for producing an unsaturated carboxylic acid, such as acrylic acid or methacrylic acid, from an alkanes, such as propane, have not been disclosed.
U.S. Pat. No. 5,380,933 noted above discloses a molybdovanadate catalyst for the oxidation of propane to acrylic acid with a yield of 52%. The catalyst contains molybdenum, vanadium, niobium and tellurium. Tellurium can become volatile at the temperatures used for the oxidation of propane to acrylic acid (350-425° C.). Catalyst life can be affected by the loss of tellurium. In addition, tellurium is an environmental hazard which must be contained or controlled with means which add to the overall process costs. The present catalyst does not contain tellurium.
Japanese patent application no. H6-218286 noted above discloses a silver-containing molybdovanadate catalyst (0.1 gram-mole of silver per 12 gram-moles of molybdenum) for conversion of propane to acrolein and acrylic acid. The catalyst also contained phosphorus, copper, barium, tellurium, iron, cerium and potassium. The overall yield for acrylic acid was less than 0.2%. The silver-containing catalyst was not shown to have any advantages over other claimed catalysts. Silver was only one of twenty-nine possible elements in the claimed catalyst.